Hydrofining employing treated alumina material in fixed beds

ABSTRACT

A hydrotreating process comprises contacting a substantially liquid hydrocarbon-containing feed stream, which contains compounds of sulfur and metals (preferably Ni and/or V), in the presence of a fixed catalyst bed comprising (a) at least one layer of impregnated substantially spherical alumina-containing particles which have been prepared by a process comprising the steps of impregnating specific starting material with at least one dissolved magnesium compound and then heating the thus impregnated material at about 500°-900° C. for improved crush strength retention. In a preferred embodiment, the fixed catalyst bed further comprises at least one layer (b) of catalyst particles comprising a refractory inorganic carrier and at least one hydrogenation promoter. A composition of matter comprising the impregnated, spherical alumina-containing particles described above, and a process for preparing them are also provided.

BACKGROUND OF THE INVENTION

This invention relates to the preparation of impregnated, substantiallyspherical alumina-containing particles having improved crush strengthretention. In another aspect, this invention relates to a process forhydrotreating hydrocarbon-containing oils, which also contain sulfur andmetal impurities, in the presence of a fixed bed comprising at least onelayer of impregnated, substantially spherical alumina-containingparticles. In still another aspect, this invention relates to the use ofsaid at least one layer of impregnated, substantially sphericalalumina-containing particles as support layer in a fixed catalyst bed.In a further aspect, this invention relates to a process forcatalytically hydrotreating hydrocarbon-containing oils in the presenceof water. In still another aspect, this invention relates to a fixedmulti-layer hydrotreating catalyst bed system comprising at least onelayer of substantially spherical alumina-containing particles.

Fixed beds of hydrotreating catalysts are used in many oil refineries.Examples of processes in which fixed hydrotreating (hydrofining)catalyst beds are used include hydrodenitrogenation hydrodesulfurizationand hydrodemetallization of heavy oils. Generally, a layer of shaped,substantially inert ceramic particles at the bottom of the fixed bedreactor is used to support a column of one or more layers ofhydrotreating catalyst. The same shaped, substantially inert materialcan also be employed as the top layer (i.e., above one or more layers ofhydrotreating catalyst) or between layers of hydrotreating catalyst, soas to provide improved flow dispersion of feed oil passing downwardlythrough the fixed catalyst bed. More recently, promoted alumina spheres,which offer some catalytic activity, have been suggested as replacementfor these substantially inert ceramic support particles which generallyhave little or no catalytic activity for hydrodesulfurization and-demetallization. However, there is an ever present need to developimproved substantially spherical alumina-containing support particleshaving higher crush strength and higher resistance to specific feedcomponents, such as water, than those presently known, so as to employthese improved alumina-containing support particles under very severehydrotreating conditions.

SUMMARY OF THE INVENTION

It is an object of this invention to provide impregnated, substantiallyspherical alumina-containing particles having high crush strengthretention. It is another object of this invention to provide a processfor making impregnated, substantially spherical alumina-containingparticles having high crush strength retention. It is still anotherobject of this invention to provide a process for hydrotreatingsubstantially liquid hydrocarbon-containing feed streams employing afixed catalyst bed comprising at least one layer of impregnated,substantially spherical alumina-containing particles having high crushstrength retention. It is a further object of this invention to providea process for hydrotreating substantially liquid hydrocarbon-containingfeed streams in the presence of water and a fixed catalyst bedcomprising at least one layer of impregnated, substantially sphericalalumina-containing particles having high crush strength retention. It isstill another object of this invention to provide a multi-layer catalystbed comprising at least one layer of impregnated, substantiallyspherical alumina-containing particles having high crush strengthretention (when exposed to oil and water under hydrotreatingconditions). It is a still further embodiment of this invention toemploy said multi-layer catalyst bed in said process for hydrotreatingsubstantially liquid hydrocarbon-containing feed streams. Furtherobjects and advantages will be apparent from the detailed descriptionand the appended claims.

In accordance with this invention, a hydrotreating process comprises thestep of contacting a substantially liquid (i.e., liquid at thehydrotreating conditions) hydrocarbon-containing feed stream, which alsocontains compounds of sulfur and metals, with a free hydrogen containinggas in the presence of a fixed catalyst bed comprising

(a) at least one layer of impregnated, substantially sphericalalumina-containing particles,

under such hydrotreating conditions as to obtain at least one liquidhydrocarbon-containing product stream having lower concentrations ofsulfur and metals than said hydrocarbon-containing feed stream;

wherein said impregnated, substantially spherical alumina-containingparticles in catalyst layer (a) have been prepared by a processcomprising the steps of

(A) impregnating (i) a starting material of substantially sphericalalumina-containing particles, which have an initial average particlediameter of at least about 0.05 inch, an initial surface area(determined by the BET/N₂ method; ASTM D3037) of at least about 20 m²/g, an initial pore volume (determined by mercury intrusion porosimetryat a pressure ranging from 0to 50,000 psig) of at least about 0.1 cc/g,and an initial content of Al₂ O₃ of at least about 80 weight-%, with(ii) a solution (preferably aqueous) comprising at least one dissolvedmagnesium compound; and

(B) heating the material obtained in step (A) at a temperature in therange of from about 500° to about 900° C. for a period of time of atleast 10 minutes, preferably for a period of time in the range of about10 minutes to about 20 hours, under such heating conditions as toconvert at least a portion of said at least one magnesium compoundabsorbed (taken up) in step (A) to magnesium oxide and to obtain amaterial having a higher retention of crush strength (measured afterexposure for about 100 hours to a liquid hydrocarbon-containing streamwhich contains at least about 0.5 weight-% sulfur, under hydrotreatingconditions at about 2250 psig total pressure, about 350 psig partialpressure of steam and about 700° F.) than said starting material.

Preferably a drying step (A1) after step (A) is carried out, so as toremove at least a portion of water from the material obtained in step(A). In this preferred embodiment, step (B) is carried out with theproduct obtained in step (A1).

In one preferred embodiment, said metals in said liquidhydrocarbon-containing feed stream comprise at least one of nickel andvanadium, preferably about 3-500 ppmw Ni and about 5-1,000 ppmw V(ppmw=parts per million parts of feed stream). In another preferredembodiment, said substantially liquid hydrocarbon-containing feed streamalso contains water (preferably about 0.5-10 volume-%). In a furtherpreferred embodiment, steam is injected into the fixed catalyst bedduring said contacting under hydrotreating conditions.

In a particularly preferred embodiment, said catalyst bed additionallycomprises

(b) at least one layer of catalyst particles [i.e., hydrotreatingcatalyst particles; different from the particles in layer (a)]comprising a refractory inorganic carrier (preferably alumina) and atleast one (i.e., one or a mixture of two or more) hydrogenation promoterselected from the group consisting of transition metals of Groups IIIB,IVB, VB, VIB, VIIB, VIII, IB and IIB of the Periodic Table (as definedin Webster's New Collegiate Dictionary, 1977) and compounds of thesemetals (preferably Y, La, Ce, Ti, Zr, Cr, Mo, W, Mn, Re, Ni, Co and Cu).The most preferred hydrogenation promoters include oxides and/orsulfides of Mo, Co, Ni and mixtures of two or more of these compounds.In addition to or in lieu of these hydrogenation promoters, one or morecompounds of phosphorus can also be present in these catalyst particles.

Also in accordance with this invention, there is provided a compositionof matter (suitable as a hydrotreating catalyst composition) comprising(preferably consisting essentially of) impregnated substantiallyspherical alumina-containing particles, having been prepared by theprocess comprising steps (A) and (B), and optionally also step (A1), asdescribed above. Further in accordance with this invention, there isprovided a process for preparing said composition of matter comprisingsteps (A) and (B), and optionally also step (A1), as described above.

Further in accordance with this invention, a fixed catalyst bed(preferably a hydrotreating catalyst bed) is provided comprising

(a) at least one catalyst bed layer of impregnated, substantiallyspherical alumina-containing particles of this invention, having beenprepared by the process composing steps (A) and (B), and optionally alsostep (A1), as described above; and

(b) at least one catalyst bed layer of catalyst particles [preferablyhydrotreating catalyst particles; different from the particles in layer(a)] comprising a refractory inorganic carrier material and ahydrogenation promoter, as defined above in the description of thehydrotreating process of this invention.

In one preferred embodiment of this invention, said impregnated,substantially spherical alumina-containing particles, which can be usedin catalyst bed layer (a), also contain at least one compound of atleast one element selected from the group consisting of Y, La, Ce, Ti,Zr, Cr, Mo, W, Mn, Re, Ni, Co, Cu, Zn and P, preferably oxide and/orsulfide of Mo and/or Co and/or Ni (more preferably containing about0.1-2.0 weight-% Mo) as hydrotreating promoters. In a more preferredembodiment, the impregnating solution used in step (A) (described abovein the description of the hydrotreating process) comprises at least onecompound of at least one of the elements listed immediately above.

In a further preferred embodiment, said at least one catalyst bed layer(a) is located as support layer below said at least one catalyst bedlayer (b). In a still further preferred embodiment, said at least onelayer (a) is located on top of said at least one catalyst layer (b). Instill another embodiment, one catalyst bed layer (a) is located belowsaid catalyst bed layer (b) and another catalyst bed layer (a) islocated above said catalyst bed layer (b). In a further embodiment,layer (a) is located between two layers (b). These configurations ofcatalyst bed layers described immediately above are preferably employedin the hydrotreating process of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the arrangement of a fixed multi-layer catalyst bed usedfor testing catalysts in hydrotreating processes.

FIG. 2 is a graph showing the dependence of crush strength (determinedafter use in hydrotreating test) of alumina-containing particles on thecalcination temperature.

FIG. 3 exhibits pore distribution curves for several alumina-containingparticles.

DETAILED DESCRIPTION OF THE INVENTION (A) Hydrotreating Process

Any suitable hydrocarbon-containing feed stream, which is substantiallyliquid at the hydrotreating conditions and contains compounds of metals(in particular nickel and/or vanadium) and sulfur as impurities, can beemployed in the hydrotreating process of this invention. Generally thesefeed streams also contain coke precursors (measured as Ramsbottomcarbon) and nitrogen compounds as impurities. Suitablehydrocarbon-containing feed streams include crude oil (crude petroleum)and heavy fraction thereof, heavy oil extracts, liquid coal pyrolyzates,liquid products from coal liquification, liquid extracts and liquidpyrolyzates from tar sands, shale oil and heavy shale oil fractions. Theprocess of this invention is particularly suited for treating heavycrudes and heavy petroleum residua, which generally have an initialboiling point (at atmospheric pressure) in excess of about 400° F.,preferably in excess of about 600° F. These heavy oil feeds generallycontain at least about 5 ppmw (parts by weight per million by weight ofhydrocarbon-containing feed) vanadium (preferably 5-1000 ppmw V), atleast about 3 ppmw Ni (preferably about 3-500 ppmw Ni), at least about0.5 weight-% sulfur (preferably about 0.5-5.0 weight-% S), about 0.2-2.0weight-% nitrogen, and about 1-20 weight-% Ramsbottom carbon residue(determined by ASTM D524). The API₆₀ gravity (measured at 60` F.) ofthese feeds is generally about 5-30 (preferably about 8-25).

The substantially liquid hydrocarbon-containing feed stream can besubstantially free of water but can, in a preferred embodiment, alsocontain at least about 0.3 weight-% water, generally about 0.3 to about20 weight-% H₂ O, preferably about 0.5 to about 10 weight-% H₂ O, morepreferably about 1.0 to about 5.0 weight-% H₂ O. Water can be residualwater which has not been removed from heavy crude oil, or water can beadded as liquid water to the hydrocarbon-containing feed stream prior toits contact with the fixed catalyst bed, or water can be added as steamto the hydrocarbon-containing feed stream prior to its contact with thefixed catalyst bed, or water can be added as steam concurrently with thehydrocarbon-containing feed stream prior to its contact with the fixedcatalyst bed. Some oil refineries use steam in this manner to alleviatecoke deposition in the fixed catalyst bed and thus retard fouling anddeactivation of the fixed catalyst bed. The hydrotreating process ofthis invention is particularly suited for feed streams that containwater because the alumina-containing particles in layer (a), inaccordance with this invention, are particularly resistant to thedetrimental effect of water during hydrotreating.

The hydrotreating process of this invention can be carried out in anyapparatus whereby an intimate contact of the fixed hydrotreatingcatalyst bed with said hydrocarbon-containing feed stream and a freehydrogen containing gas is achieved, under such conditions as to producea hydrocarbon-containing product having reduced levels of metals (inparticular Ni and V) and sulfur. Generally, a lower level of nitrogenand Ramsbottom carbon residue and higher API gravity are also attainedin this hydrotreating process. The hydrotreating process of thisinvention can be carried out as a batch process or, preferably, as acontinuous down-flow process, more preferably in a tubular reactorcontaining one or more fixed catalyst beds (as will be described later)or in a plurality of fixed bed reactors in parallel or in series. Thehydrocarbon-containing product stream can be distilled, e.g., in afractional distillation unit, so as to obtain fractions having differentboiling ranges.

Any suitable reaction time (contact time) between the fixed catalystbed, the hydrocarbon-containing feed stream, the hydrogen-containing gasand, optionally, steam can be utilized. In general, the reaction timewill be in the range of from about 0.05 hours to about 10 hours,preferably from about 0.4 to about 5 hours. In a continuous fixed bedoperation, this generally requires a liquid hourly space velocity (LHSV)in the range of from about 0.10 to about 10 cc of feed per cc ofcatalyst per hour, preferably from about 0.2 to about 2.5 cc/cc/hr.

The hydrotreating process employing the fixed catalyst bed of thepresent invention can be carried out at any suitable temperature. Thereaction temperature will generally be in the range of about 250° C. toabout 550° C. and will preferably be in the range of about 300° C. toabout 450° C. Higher temperatures do improve the removal of impuritiesbut temperatures which will have adverse effects on the hydrocarboncontaining feed stream, such as excessive coking, will usually beavoided. Also, economic considerations will usually be taken intoaccount in selecting the operating temperature.

Any suitable pressure may be utilized in the hydrotreating process. Thereaction pressure will generally be in the range from of aboutatmospheric pressure (0 psig) to up to 5,000 psig. Preferably, thepressure will be in the range of from about 100 to about 2500 psig.Higher pressures tend to reduce coke formation, but operating at highpressure may be undesirable for safety and economic reasons.

Any suitable quantity of free hydrogen can be added to the hydrotreatingprocess. The quantity of hydrogen used to contact the hydrocarboncontaining feed stream will generally be in the range of from about 100to about 10,000 standard cubic feet H₂ per barrel of hydrocarboncontaining feed stream and will more preferably be in the range of fromabout 1,000 to about 5,000 standard cubic feed H₂ per barrel of thehydrocarbon containing feed stream. Either pure hydrogen or a freehydrogen containing gas mixture (e.g., H₂ and CH₄, or H₂ and CO, or H₂and N₂) can be used.

If desired, the hydrotreating process of this invention may comprise thestep of adding at least one added thermally decomposable metal compoundinto the hydrocarbon-containing feed stream prior to its being contactedwith the catalyst composition of this invention. The metal in the addedthermally decomposable metal compound is selected from compounds ofmetals of Group IIIB, IVB, VIB, VIIB, VIII, IB and IIB of the PeriodicTable (as defined above). Preferred metals are molybdenum, tungsten,manganese, chromium, zirconium and zinc. Molybdenum is a particularlypreferred metal which may be introduced as a carbonyl, acetate,acetylacetonate, carboxylate (e.g., octoate), naphthenate, mercaptide,dithiophosphate or dithiocarbamate. Molybdenum hexacarbonyl, molybdenumdithiophosphate and molybdenum dithiocarbamate are particularlypreferred additives. The life of the catalyst composition and theefficiency of the demetallization process is improved by introducing atleast one of the above-cited decomposable metal compounds into thehydrocarbon containing feed, which also contains metals such as nickeland vanadium. These additives can be added continuously orintermittently and are preferably added at a time when the catalystcomposition of this invention has been partially deactivated so as toextend its life. Any suitable concentration of the additive may be addedto the hydrocarbon containing feed stream to result in a concentrationof the metal (preferably molybdenum) of said decomposable compounds inthe range of from about 1 to about 1,000 parts per million by weight andmore preferably in the range of about 5 to about 100 parts per millionin said feed stream.

At least a portion of the hydrotreated product stream which has beenproduced in the process of this invention can subsequently be cracked,e.g., in a fluidized catalytic cracking unit, employing zeolite- orclay-containing cracking catalyst, under such conditions as to producelower boiling hydrocarbon materals, such as gasoline and kerosene,suitable for use as fuels and other useful products. It is within thescope of this invention to hydrotreat the product stream having reducedcontents of metals and sulfur in a second hydrotreating process using adifferent fixed catalyst bed, such as zinc titanate-supported Ni/MoO₃catalysts, for further removal of sulfur and other impurities (e.g.,metals) before the product stream is introduced into a cracking reactorand treating under cracking conditions.

(B) Composition of Matter and Preparation Thereof

As has been described in the "Summary of the Invention", theimpregnated, substantially spherical alumina-containing particles ofthis invention are prepared by a process comprising the steps ofimpregnating and then heating a suitable starting material undersuitable conditions, so as to obtain a product having a specific set ofproperties. Any suitable substantially spherical alumina containingparticles which have the following initial parameters can be used assaid starting mateial for step (A): average particle diameter of atleast about 0.05 inch, preferably in the range of from about 0.05 toabout 1.5 inch, more preferably from about 0.1 to about 1.0 inches;surface area (determined by the BET/N₂ method; ASTM D3037) of at leastabout 20 m² /g, preferably in the range of from about 40 to about 600 m²/g, more preferably in the range of from 100 to about 400 m² /g; a porevolume, as determined by mercury intrusion porosimetry (carried out atroom temperature and a mercury pressure varying from 0 psi to about60,000 psi, using an Autopore 9200 instrument of Micromeritics,Norcross, GA), of at least about 0.1 cc/g, preferably in the range offrom about 0.2 to about 1.0 cc/g., more preferably from about 0.3 toabout 0.7 cc/g; and content of alumina, which generally is a mixture ofgamma-alumina and amorphous alumina, of at least about 80 weight-% Al₂O₃, preferably in the range of from about 90 to about 99 weight-% Al₂O₃, more preferably from about 93 to about 98 weight-% Al₂ O₃. Thepreferred starting material has a normalized crush strength perparticle, determined as side plate crush strength by means of amechanical force gauge, such as the one described in Example I, of atleast 100 lb. per inch diameter per particle, preferably in the range offrom about 100 to about 400 lb. per inch diameter per particle; and a Nacontent of less than about 3.0 weight-%, more preferably less than about1.0 weight-% Na, most preferably less than about 0.5 weight-% Na. Apresently particularly preferred starting material is a commerciallyavailable spherical, alumina-containing Claus catalyst material that ismarketed by the Aluminum Company of America, Pittsburgh, PA under theproduct designation of S-100 (see Example II).

Preparation step (A), as described above, can be carried out in anysuitable manner. The solvent in the impregnating solution used in step(A) generally comprises water, and preferably consists essentially ofwater. Suitable solvents which can be used besides water are alcoholssuch as methanol, ethanol, ethylene glycol and the like, acetone, esterssuch as ethyl acetate and the like. However, these non-aqueous solventsare presently not preferred.

The solute in the impregnating solution used in step (A) can be anymagnesium compound that is at least partially soluble in water ormixtures of two or more of these magnesium compounds. Non-limitingexamples of suitable Mg compounds are Mg(NO₃)₂, Mg(HCO₃)₂, Mg(HSO₄)₂,MgSo₄, Mg acetate and the like, preferably Mg(NO₃)₂. The concentrationof the Mg compound in the impregnating solution generally is in therange of from about 10⁻⁴ to about 2.0 mol/l of Mg (i.e., g-atoms Mgcontained in the dissolved Mg compound(s) per liter solution),preferably from about 0.01 to about 1.0 mol/l Mg.

The impregnation of the alumina-containing starting material with theimpregnating solution in step (A) can be carried out in any suitablemanner. Preferably, the starting material is soaked with theimpregnating solution, more preferably with agitation such as mechanicalstirring, for a period of time long enough (preferably about 0.5-3 days)to allow said at least one dissolved Mg compound to penetrate into thesubstantially spherical, alumina-containing particles of the startingmaterial, more preferably to the core of these particles. Any suitableweight ratio of said starting material to the impregnating solution canbe employed. Preferably, the weight ratio of said starting material tosaid impregnating solution will be in the range of from about 0.1:1 toabout 2.0:1, more preferably from about 0.3:1 to about 1.2:1. Eventhough presently not preferred, other impregnating methods can beapplied, such as spraying of the impregnating solution, which comprisesat least one dissolved Mg compound, onto the substantially spherical,alumina-containing particles of the starting material.

Even though the material obtained in step (A) can be directly processedin step (B), it is presently preferred to substantially dry theimpregnated material obtained in step (A) in drying step (A1). Thedrying step (A1) is generally carried out in air or an inert gas, at atemperature ranging from about 25° C. to about 200° C. (preferably50°-100° C.) so as to remove the greatest portion of water from themixture obtained in step (B). Vacuum conditions may be employed but arepresently not preferred. The at least partially dried mixture generallycontains less than about 20 weight-% water. The rate of drying iscontrolled so as to avoid surges of water vapor that can cause theimpregnating solution to splatter and can cause the solute toexcessively accumulate in surface regions of the solid particles.Depending on the drying temperature and specific drying conditions (suchas extent of air movement; thickness of the solid layer to be dried),the drying time ranges generally from about 0.5 hour to about 100 hours,preferably from about 1 hour to about 30 hours.

The impregnated alumina-containing material obtained in step (A), oralternatively step (A1), is heated (calcined) at a temperature in therange of from about 500° to about 900° C., preferably from about 550° toabout 800° C., more preferably from about 600° to about 750° C. Theheating time is at least 10 minutes, preferably in the range of fromabout 10 minutes to 20 hours, more preferably from about 0.5 to about 10hours. The pressure can be atmospheric (preferred) or subatmospheric orsuperatmospheric. The heating process can be carried out in a freeoxygen containing gas atmosphere, such as air, or in an inert or in areducing gas atmosphere. Presently heating in an O₂ -containing gas ispreferred. It is believed that heating in an O₂ -containing gas insuresthat Mg compounds taken up by the starting material in step (A) issubstantially converted to MgO in step (B). The gas atmosphere maycontain water vapor, but the amount of water vapor should be minimizedto less than about 10 volume percent.

Generally, the above-described heating (calcining) of the impregnatedspherical, alumina-containing material results in a tolerable decreasein surface area, in a slight increase in total pore volume, but in asubstantial increase of the pore volume in pores having a pore diameterin the 40-200 Angstroms (A) range. Preferably, the impregnated,substantially spherical alumina-containing particles in catalyst layer(a), obtained by the preparation process of this invention, have a porevolume of pores in the 40-200 A pore diameter range in excess of about50%, more preferably from about 50 to about 90% of the total porevolume. Preferably, the total BET/N₂ surface area of the impregnated,substantially spherical particles of this invention is in the range offrom about 50 to about 300 m² /g, and the total pore volume (determinedby mercury porosimetry, discussed above) is in the range of from about0.3 to about 0.8 cc/g. The Mg content of the calcined substantiallyspherical material of this invention preferably contains at least about0.006 weight-% Mg (i.e., about 0.01 weight-% MgO), more preferably about0.06 to about 6.0 weight-% Mg (i.e., about 0.1 to about 10 weight-%MgO), more preferably about 0.3 to about 4.0 weight-% Mg (i.e., about0.5 to about 6.6 weight-% MgO).

The crush strength of the impregnated, substantially sphericalalumina-containing particles of this invention is preferably measuredafter they have been used in a hydrotreating process in the presence ofwater, as has been described above and also in Example I, so as todetermine the retention of initial crush strength under these severehydrotreating conditions (about 2250 psi total pressure, about 400 psipartial pressure of steam, 700° F., 100 hours; with at least about 0.5weight-% sulfur in the hydrocarbon-containing feed). The thus determinedcrush strength generally exceeds 150 lb. per inch diameter per particleand preferably is in the range of about 150 to about 350lb./inch/particle.

The impregnated, substantially spherical alumina-containing particles ofthis invention can be promoted with at least one element or compound atleast one element (i.e., one or mixture of two or more) selected fromthe group consisting of Y, La, Ce, Ti, Zr, Hf, Cr, Mo, W, Mn, Re, Ni,Co, Cu, Zn, P (as phosphite and/or phosphate), preferably Mo, Ni and Co,more preferably Mo. The total promoter level generally is relatively lowand suitably ranges from about 0.01 to about 3.0 weight-% of said atleast one element, preferably from about 0.1 to about 2.0 weight-%, morepreferably from about 0.2 to about 1.0 weight-% of said at least oneelement (most preferably Mo).

Any suitable technique for promoting the particles of this invention canbe employed, preferably the impregnating solution used in step (A)contains one or more of the above-described promoters besides (NH₄)₂SO₄. The thus obtained particles, which additionally contain at leastone promoter compound, then undergo step (B), optionally after step(A1), as described above. It is, of course, possible (yet presently notpreferred) to carry out step (A) without having any transition metaland/or phosphorus promoter compound present in the impregnatingsolution, and to impregnate the calcined material obtained in step (B)with a solution containing at least one promoter compound, followed bydrying and calcining (preferably at about 500°-900° C.) of the thustwice-impregnated material (so as to at least partially convert the atleast one transition metal compound to oxides of said metal). Generallythe crush strength of the impregnated, substantially sphericalalumina-containing particles is not substantially affected by thepresence of one or more promoters.

(C) Fixed Catalyst Bed

In accordance with this invention, a fixed catalyst bed, suitable forhydrotreating substantially liquid hydrocarbon-containing feed streamswhich also contain sulfur and metal compounds (as has been describedearlier for one embodiment of this invention), is provided comprising atleast one layer (a) of the impregnated, substantially sphericalalumina-containing material of this invention.

In a preferred embodiment of this invention the fixed catalyst bedcomprises at least one layer (a), as described above, and at least onelayer (b) of catalyst particles, different from those in layer (a). Thecatalyst particles in layer (b) generally comprise an inorganicrefractory carrier. Non-limiting examples of such inorganic refractorycarrier materials are those that comprise (preferably consistessentially of) alumina (preferred), aluminum phosphate, silica,titania, zirconia, zirconium phosphate, ceria, boria, magnesia,silica-alumina, titania-silica, titania-alumina. In addition to thecarriers, the catalyst particles in catalyst bed layer (b) comprise atleast one promoter selected from compounds of metals of Groups IIIB,IVB, VB, VIB, VIIB, VIII, IB and IIB of the Periodic Table. Presentlypreferred promoters are compounds of metals selected from the groupconsisting of Y, La, Ce, Ti, Zr, Cr, Mo, W, Mn, Re, Ni, Co and Cu, morepreferably oxides and/or sulfides of these metals, most preferably Mo,Ni, Co, and mixtures of any of these metal oxides and sulfides.Phosphorus compounds of these metals can also be present. Generally thetotal level of promoter ranges from about 0.5 to about 30 weight-%,preferably from about 1 to about 15 weight-%, based on the elementalmetal. Generally the BET/N₂ surface area of the particles in layer (b)is in the range of from about 50 to about 500 m² /g, and their porevolume (measured by mercury porosimetry) is in the range of from about0.2 to about 2.0 cc/g.

The catalyst particles in layer (b) can be prepared by any suitabletechnique such as contacting of the carrier (preferably alumina) withone or more solutions containing one or more compounds of the promotermetals (plus, optionally, one or more compounds of phosphorus) andsubsequent drying and calcining (this method presently being preferred)as has been described for promoted particles in layer (a); or bycoprecipitation e.g., of hydrogels of alumina and promoter metal (e.g.,Ni, Co, Mo), followed by drying and calcining. Suitable commerciallyavilable catalyst materials for layer (b) are described in Example I.

Layers (a) and (b) can be arranged in the fixed catalyst bed of thisinvention in any suitable manner. In one preferred embodiment layer (a)is placed as support layer below at least one catalyst layer (b). Inanother embodiment, layer (a) is placed as a cover layer on top of atleast catalyst layer (b). In a further embodiment, layer (a) is placedbetween at least two catalyst layers (b). In a still further embodiment,in which at least three layers (a) and at least two catalyst layers (b)(which are different from each other) are employed, one layer (a) isplaced on top of said at least two catalyst layers (b), one layer (a) isplaced as interlayer between two different catalyst layers (b), and athird layer (a) is placed below said at least two lower catalyst layer(b). Another suitable catalyst bed arrangement is shown in FIG. I. Theweight ratio of each catalyst layer (a) to each catalyst layer (b) isgenerally in the range of from about 1:100 to about 1:1, preferably fromabout 1:20 to about 1:5.

The dimensions of catalyst bed layer (a) comprising the substantiallyspherical alumina-containing particles obtained by the above-describedheating process are not critical and depend on the dimension of thehydrotreating reactor that holds the fixed catalyst bed. Generally theheight of each layer (a) ranges from about 1 to about 50 feet incommercial hydrotreating operations. It is within the scope of thisinvention to have additionally inert particles present (up to 50weight-%) in layer (a), such as inert ceramic particles, in particularDenstone D-57. The height of each catalyst layer (b) can vary widely,depending on the particular reactor dimensions.

If desired, the fixed catalyst bed of this invention can be sulfided bytreatment with a fluid stream that contains sulfur compounds, generallyprior to said hydrotreating process. Non-limiting examples of such fluidstreams are solutions or mercaptans, mercaptoalcohols, organic sulfidesand organic disulfides in a suitable organic solvent (such as gas oiland other petroleum fractions), and gas streams that comprise H₂ S, suchas mixtures of H₂ and H₂ S. This sulfiding procedure is generallycarried out at an elevated temperature (preferably at about 400°-700°F.) for a period of time sufficient (preferably from about 0.5-20 hours)so as to convert at least a portion of any compounds of one or moremetals contained in particles of layer (b), and optionally also inparticles of layer (a), to sulfides of said one or more metals.

In general, the fixed catalyst bed of this invention is utilizedprimarily for demetallization and desulfurization. The time in which thefixed catalyst bed of this invention will maintain its activity for theabove process will depend upon the hydrotreating conditions and thecomposition of the hydrocarbon-containing feed. Generally, thetemperature of the hydrotreating process is gradually increased tocompensate for loss of catalyst activity due to fouling (e.g., due todeposition of coke and metals as the catalyst). The entire fixedcatalyst bed or one or more layers of the fixed catalyst bed can, ifdesired, be regenerated when the catalytic activity has dropped below adesired level. Catalyst regeneration can be carried in-situ bydiscontinuing the flow of hydrogen and of the hydrocarbon-containingfeed streams, purging the fixed bed reactor with an inert gas (e.g.,N₂), and then heating the fixed catalyst bed in a free oxygen-containinggas atmosphere (such as air), under such conditions as to removecarbonaceous materials and to at least partially convert sulfides oftransition metals such as Mo, Co and/or Ni back to their oxides and/orphosphates. Preferably, however, the fixed bed layers are removed fromthe cooled hydrotreating reactor after said purging and are transferredto another reactor where the catalyst regeneration takes place.Generally the catalyst regeneration step is carried out at about400°-600° C. and at a pressure of about 0-1,000 psig.

The following examples are presented in further illustration of theinvention and are not to be considered as unduly limiting the scope ofthis invention.

EXAMPLE I

This example illustrates the evaluation of catalyst bed supportparticles in oil hydrotreating tests, in the presence of steam. Thepurpose of this evaluation procedure is to determine thehydrodemetallization activity and the retention of crush strength ofthese support particles under severe hydrotreating conditions, in thepresence of steam.

The catalyst bed arrangement (simulating proportions of a typicalrefinery bed loading) which was used in the evaluation tests is shown inFIG. 1. The catalyst bed column had a diameter of about 0.75 inches.Particles A were substantially spherical alumina-containing particles,which can be any of the particles A1 through A15 described in moredetail in Example II. Material B was a commercial alumina-supportedhydrotreating catalyst comprising 0.9 weight-% Co, 0.5 weight-% Ni and7.5 weight-% Mo, having a BET/N₂ surface area of 174 m² /g and a porevolume of 0.63 cc/g (measured by mercury intrusion porosimetry).Material C was a commercial alumina-based hydrotreating catalystcomprising 3.1 weight-% Ni, 7.9 weight-% Mo and 4.6 weight-% Ti having aBET/N surface area of 140 m² -g and a pore volume (by Hg intrusionporosimetry) of 0.5 cc/g. Material D was a commercial alumina-basedhydrotreating catalyst comprising 2.4 weight-% Co and 6.7 weight-% Mo,having a BET/N₂ surface area of 290 m² /g and pore volume (by Hgintrusion porosimetry) of 0.47 cc/g.

A heavy oil-water mixture containing about 4-8 volume-% H₂ O was pumpedto a metallic mixing T-pipe where it was mixed with a controlled amountof hydrogen gas. The heavy oil was a Maya 400F+ resid having an API⁶⁰gravity of 14.0, containing 3.8 weight-% sulfur and about 350 ppmw(Ni+V) (parts by weight of Ni+V per million parts by weight of oilfeed). The oil/water/hydrogen mixture was pumped downward through astainless steel trickle bed reactor which contained the multi-layercatalyst bed described above (see FIG. I). The tubular reactor was about28.5 inches long, has an inner diameter of about 0.75 inches, and wasfitted inside with a 0.25 inch O.D. axial thermocouple well. The reactorwas heated by a 3-zone furnace. The reactor temperature was usuallymeasured in four locations along the reactor bed by a travelingthermocouple that was moved within the axial thermocouple well.

Generally, the hydrotreating conditions were as follows: reactiontemperature of about 690°-710° F.; liquid hourly space velocity (LHSV)of about 0.3 cc/cc catalyst/hour; about 2,250 psig total pressure; about330-400 psig H₂ O (steam) partial pressure; time on stream: about100-200 hours. When it was desired to determine the desulfurization anddemetallization activity of the catalyst bed, the liquid product wasfiltered through a glass filter and analyzed for sulfur, nickel andvanadium by plasma emission analysis.

After completion of the hydrotreating test, the reactor with catalystbed was flushed with xylene so as to remove undrained oil. Thereafter,nitrogen gas was passed through the xylene-washed catalyst bed so as todry it. The various catalyst layers were carefully removed. Particles A,B or C were tested for crush strength in a Mechanic Force Gauge D-75M ofHunter Spring, Division of Ametek, Hot Field, PA. A single sphere of Aor B or C, the average diameter of which had been measured, was placedbetween the metal plates of D-75M, and the plates were slowly movedtoward one another by means of an electric motor. The force applied tothe plates was displayed by a gauge. The force necessary to fracture(crush) a catalyst sphere was recorded as the crush strength of thesphere. The normalized crush strength, defined as crush strength of asphere divided by its average particle diameter (lb/sphere/inchdiameter), was calculated.

EXAMPLE II

This example illustrates the preparation of the substantially sphericalalumina-containing particles of this invention and of otheralumina-containing catalyst bed particles.

Control Particles A1 were spherical, Co/Mo-promoted alumina particles,marketed by Shell Chemical Company, Houston, TX under the productdesignation "Shell 544", suitable as support balls for hydrotreatingcatalyst beds. Pertinent properties of Particles A1 were: diameter of1/6 inch; cobalt content of 1.7 weight-%; molybdenum content of 5.3weight-%; surface area of 300+ m² /g; total pore volume of 0.47 cc/g;loss on ignition (LOI; weight loss when heated to 482° C.) of 0.8weight-%; compacted bulk density (compacted loading density) of about0.83 g/cc; and side plate crush strength of 30+ lb/particle (i.e., about190 lb/particle/inch diameter).

Control Particles A2 were substantially spherical, substantiallyunpromoted alumina-containing particles having an average particlediameter of 1/4 inch; a BET/N₂ surface area of about 325 m² /g; a totalpore volume of about 0.50 cc/g; and average normalized individual ballcrush strength of about 240 lb/particle/inch diameter (i.e., the actualcrush strength of a 1/4" sphere was about 60 lb/particle); Al₂ O₃content of about 94.6 weight-%; Na₂ O content of about 0.35 weight-%;and LOI content (weight loss when heated from 250° C. to 1200° C.; ameasure of hydroxyl content) of 5.0 weight-%. Particles A2 were suppliedby Aluminum Company of America, Pittsburgh, PA under the productdesignation of S-100.

Control Particles A3 were obtained when Control Particles A2 were heatedat about 650° C. for about one hour.

Control Particles A4 were obtained by soaking 27.0 grams of ControlParticles A2 with 50 cc of an aqueous solution containing 3.17 grams ofdissolved Ca(NO₃)₂.4H₂ O for about 0.5-3 days, decanting excesssolution, drying the thus impregnated particles and then calcining themat about 650° C. for about 2 hours in air. Control Particles A4contained about 1.6 weight-% CaO.

Control Particles A5 were prepared essentially in accordance with theprocedure for Particles A4, except that 16.5 grams of Ca(NO₃)₂.4H₂ O (in50 cc solution) were employed so as to provide particles containingabout 8.0 weight-% CaO.

Invention Particles A6 were prepared essentially in accordance with theprocedure for Particles A4, except that 3.4 grams of Mg(NO₃)₂.6H₂ O (in50 cc solution) were employed (in lieu of dissolved Ca nitrate), so asto provide particles containing about 1.2 weight-% MgO.

Invention Particles A7 were prepared essentially in accordance with theprocedure for Particles A4, except that 17.9 grams of Mg(NO₃)₂.6H₂ O (in50 cc solution) were employed (in lieu of Ca nitrate), so as to provideparticles containing about 5.6 weight-% MgO.

Control Particles A8 were obtained by soaking 27.0 grams of ControlParticles A2 with 25 cc of an aqueous solution containing 0.82 grams of(NH₄)₆ Mo₇ O₂₄.4H₂ O for about 3 days, decanting excess solution, dryingthe impregnated particles at 120° C. and calcining them in air at 650°C. for 1 hour. Calcined Particles A8 contained 0.3 weight-% Mo.

Control Particles A9 were prepared essentially in accordance with theprocedure for Particles A8, except that the aqueous impregnatingsolution additionally contained 0.184 grams ZnCl₂. Calcined Particles A9contained 0.3 weight-% Mo and about 0.2 weight-% ZnO.

Control Particles A10 were prepared essentially in accordance with theprocedure for Particles A8, except that the aqueous impregnatingsolution additionally contained 1.84 grams ZnCl₂. Calcined Particles A10contained 0.3 weight-% Mo and about 2.3 weight-% ZnO.

Invention Particles A11 were prepared essentially in accordance with theprocedure for Particles A8, except that the aqueous impregnatingsolution additionally contained 0.035 grams Mg(NO₃)₂.H₂ O. Calcinedparticles A11 contained 0.3 weight-% Mo and about 0.01 weight-% MgO.

Invention Particles A12 were prepared essentially in the same manner asParticles A11, except that 0.35 gram Hg(NO₃)₂.H₂ O was used. Calcinedparticles A12 contained 0.3 weight-% Mo and about 0.1 weight-% MgO.

Invention Particles A13 were prepared essentially in the same manner asParticles A11, except that 1.73 grams Mg(NO₃)₂.H₂ O were used. CalcinedParticles A13 contained 0.3 weight-% Mo and about 0.6 weight-% MgO.

Invention Particles A14 were prepared essentially the same as ParticlesA13, except that calcined Particles A14 contained 0.3 weight-% Mo andabout 1.2 weight-% MgO.

Invention Particles A15 were prepared essentially the same as ParticlesA13, except that calcined Particles A15 contained 0.3 weight-% Mo andabout 5.6 weight-% MgO.

EXAMPLE III

This example illustrates the beneficial effect of the impregnation ofspherical alumina particles with a Mg compound on the crush strength ofthe calcined particles, measured after hydrotreating in the presence ofsteam in accordance with the procedure described in Example I. Testresults are summarized in Table I.

                                      TABLE I                                     __________________________________________________________________________                 Weight-% Mo                                                                           Additional                                                                          Weight-% of                                                                            Crush Strength                            Run     Particle                                                                           in Particle                                                                           Promoter                                                                            Addit. Promoter.sup.1                                                                  (Lb Per Particle)                         __________________________________________________________________________    1 (Control)                                                                           A3   0       None  --       11.4                                      2 (Control)                                                                           A4   0       CaO   1.6      16.0                                      3 (Control)                                                                           A5   0       CaO   8.0       5.9                                      4 (Invention)                                                                         A6   0       MgO   1.2      21.8                                      5 (Invention)                                                                         A7   0       MgO   5.6      22.0                                      6 (Control)                                                                           A8   0.3     None  --       14.7                                      7 (Control)                                                                           A9   0.3     ZnO   0.2      13.5                                      8 (Control)                                                                            A10 0.3     ZnO   2.3      14.9                                      9 (Invention)                                                                          A11 0.3     MgO    0.01    16.7                                      10 (Invention)                                                                         A12 0.3     MgO   0.1      17.6                                      11 (Invention)                                                                         A13 0.3     MgO   0.6      15.7                                                                          (repeated: 24)                            12 (Invention)                                                                         A14 0.3     MgO   1.2      30.8                                      13 (Invention)                                                                         A15 0.3     MgO   5.6      31.1                                      __________________________________________________________________________     .sup.1 given as weight% metal oxide (i.e. CaO or MgO or ZnO)             

The above-described tests results clearly show that, surprisingly, theimpregnation of spherical alumina-containing particles with a Mgcompound was beneficial for the crush strength retention of calcinedparticles in hydrotreating test runs employing steam. This result isquite surprising because no such advantage of the impregnation ofalumina-containing particles with compounds of Ca or Zn was observed.Furthermore, the average initial crush strength of calcined Mg-treatedand untreated alumina-containing particles, i.e., the crush strength ofthose particles before use in hydrotreating tests employing steam wasapproximately the same: about 55 lb per 1/4 inch particle.

Additional tests showed that incorporating the Mg compound into ControlParticles A3 or A8 by soaking with the impregnating solution (containingMg nitrate), as described for Particles A6, A7 and A11-15, was moreeffective, in terms of crush strength (after hydrotreatment in thepresence of steam) and also in terms of penetration of the Mg compoundinto the interior of the alumina-containing particles (as determined byelectron microprobe analysis), than spraying of the impregnatingsolution into Particles A3 or A8. In the latter case, the Mg compoundhad penetrated in A3 or A8 particles at a depth of only up to about 2microns from the surface; whereas soaking for about 1-3 days resulted ina substantially even distribution of the Mg compound substantiallythroughout the entire alumina-containing particles of this invention.

EXAMPLE IV

This example illustrates the effect of the heating (calcination)conditions on pertinent physical properties of alumina-containingspheres. A2 particles of about 1/8 inch diameter that had beenimpregnated with about 0.3 weight-% Mo were heated in air attemperatures ranging from 400° C. to 900° C. for about 1 hour, (so as toprepare Particles A8). The crush strength of the thus calcined particles(diameter: 1/8 inch) was determined in accordance with the proceduredescribed in Example I. Tests results are summarized in Table II and areplotted in FIG. 2.

                  TABLE II                                                        ______________________________________                                                    Crush      Normalized                                             Calcination Strength   Crush Strength                                         Temp. (°C.)                                                                        (lb/Particle)                                                                            (lb/Inch Diameter)                                     ______________________________________                                        400         1.88       15.0                                                   500         3.42       27.4                                                   600         4.37       35.0                                                   700         4.80       38.4                                                   800         3.95       31.6                                                   900         1.65       13.2                                                   ______________________________________                                    

Data in Table II and FIG. 2 clearly show that maximum crush strength(after hydrotreating in the presence of steam) was attained when thealumina spheres (containing 0.3 weight-% Mo) were calcined at atemperature in the range of from about 550° to about 800° C., preferablyfrom about 600° to about 750° C.

The effect of the calcination time, at a calcination temperature of 650°C., is shown in Table III.

                  TABLE III                                                       ______________________________________                                        Calcination  Crush Strength                                                                            Crush Strength                                       Time (minute)                                                                              (lb/Particle)                                                                             (lb/Inch Diameter)                                   ______________________________________                                        20           7.01        56.1                                                 40           7.25        58.0                                                 60           7.20        57.6                                                 90           6.68        53.4                                                 120          6.41        51.3                                                 240          5.22        41.8                                                 ______________________________________                                    

Data in Table III show that a calcination time of about 20-90 minuteswas suitable for 1/8 inch diameter alumina-containing Particles A8.Prolonged calcining had a detrimental effect.

Based on the above-described test results, it is concluded that thepreferred heating conditions in step (A) for preparing theMg-impregnated, substantially spherical alumina-containing particles ofthis invention will also comprise a temperature of about 550°-800° C.(more preferably about 600°-750° C.) and a heating time of about 20-90minutes.

EXAMPLE V

The effect of the calcination temperature on the pore volumedistribution of Particles A1, A2 and A3 was investigated. Pore volumeand pore diameter of these particles were determined by measuringintrusion porosimetry (carried out at room temperature at a mercuryranging from 0 psi to 60,000 psi, using an Autopore 9200 instrument ofMicromeritics, Norcross, GA). In FIG. 3, pore volume was plotted versuslogarithm of pore diameter for A1, A2 and two A3 samples. FIG. 4 showsthat A1 (Shell 544, as received; 1/6" diameter) and of A2 (Alcoa S-100,as received; 1/16" diameter) had very similar pore distributions,whereas the pore distributions of the two A3 samples (obtained byheating 1/16" A2 particles at 600° C. and 800° C., respectively, forabout 3 hours), differed significantly from those of A1 and A2. The mostsignificant changes that resulted when A2 (S-100) particles were heatedto 600° C. and 800° C., respectively, (so as to make A3 particles), wasa shift toward a substantially greater portion of pores in the 40-200 Apore diameter range. About 80% of the total pore volume of A3 was inpores of the 40-200 Angstrom range, whereas the percentage of the totalpore volume of A1 and A2 in the 40-200 Angstrom pore diameter range wasonly about 40%.

Based on the above-described test results, it is concluded that heatingat 600°-800° C. in step (A) for preparing the impregnated, substantiallyspherical alumina-containing particles of this invention will have avery similar effect in the pore volume distribution of theMg-impregnated particles of this invention as the above-described effecton the pore volume distribution of Particles A3.

The total pore volume of the Mo-impregnated alumina spheres A3 rangedfrom about 0.5 to about 0.6 cc/g when the calcination was carried outfor 16 hours at a temperature in the range of from about 400° C. toabout 800° C. Thus, the effect of the calcination temperature on thetotal pore volume of calcined spheres A3 was rather insignificant. Basedon these results, it is concluded that the total pore volume of theMg-impregnated, substantially spherical alumina-containing particles ofthis invention (such as Particles A7, A8 and A11 through A15) will alsovary only insignificantly with the calcination temperature.

EXAMPLE VI

This example illustrates the improved performance of Particles A8 (with0.3 weight-% Mo) in prolonged hydrotreating tests versus commercialParticles A1 and A2. Crush strength results, obtained substantially inaccordance with the hydrotreating procedure described in Example I, aresummarized in Table IV. Hydrotreating conditions were: 2200 psig totalpressure; 760° F.; 110 psi steam pressure, LHSV of 0.1 cc/cccatalyst/hour. The resid feed contained about 2.0 weight-% sulfur andabout 60 ppmw (Ni+V).

                  TABLE IV                                                        ______________________________________                                               Hours on Stream:                                                              0     16       30      140   270  360                                  Particles.sup.1                                                                        Crush Strength (lb/Particle)                                         ______________________________________                                        1/6" A1  35      11       N/A   N/A   N/A  N/A                                 1/4" A2 58      11       N/A   N/A   N/A  N/A                                 1/4" A4 55      39       37    34    38   38                                  1/4" A4  100+    80+      80+  80+   80+  80+                                 1/8" B  49      N/A      42    N/A   N/A  N/A                                ______________________________________                                         .sup.1 Fractions indicate particle diameter expressed in inches.         

Test data in Table IV clearly show a significant improvement in crushstrength retention of Particles A8 over commercial Particles A1 and A2,after use in the several hydrotreating runs in the presence of steam, asdescribed in Example I. Based on these results and based on the factthat the Mg-impregnated, substantially spherical alumina-containingParticles of this invention have a higher crush strength retention thatParticles A8 (See Example III, it is concluded that the Mg-impregnated,substantially spherical alumina-containing particles of this inventionwill also be superior to commercial Particles A1 and A2, in terms ofcrush strength retention.

Reasonable variations and modifications are possible within the scope ofthe disclosure and appended claims.

That which is claimed is:
 1. A hydrotreating process comprising the stepof contacting a substantially liquid hydrocarbon-containing feed stream,which also contains compounds of sulfur and metals, with a free hydrogencontaining gas in the presence of a fixed catalyst bed comprising(a) atleast one layer of impregnated, substantially sphericalalumina-containing particles and (b) at least one layer of hydrotreatingcatalyst particles comprising a refractory inorganic carrier materialand at least one hydrogenation promoter selected from the groupconsisting of transition metals belonging to Groups IIIB, IVB, VB, VIB,VIIB, IB and IIB of the Periodic Table and compounds of said transitionmetals; under such hydrotreating conditions as to obtain at least oneliquid hydrocarbon-containing product stream having lower concentrationsof sulfur and metals than said hydrocarbon-containing feed stream;wherein said impregnated, substantially spherical alumina-containingparticles in catalyst layer (a) have been prepared by a processcomprising the steps of (A) impregnating (i) a starting material ofsubstantially spherical alumina-containing particles, which have aninitial average particle size of at least about 0.05 inch, an initialsurface area, determined in accordance with ASTM method D3037, of atleast about 20 cm² /g, an initial pore volume, determined by mercuryintrusion porosimetry, of at least about 0.1 cc/g, and an initialcontent of Al₂ O₃ of at least about 80 weight-%, with (ii) a solutioncomprising at least one dissolved magnesium compound; and (B) heatingthe material obtained in step (A) at a temperature in the range of fromabout 500° to about 900° C. for a period of time of at least 10 minutes,under such heating conditions as to convert at least a portion of saidat least one magnesium compound absorbed in step (A) to magnesium oxideand to obtain a material having a higher retention of crush strength,measured after exposure for about 100 hours to a liquidhydrocarbon-containing stream which contains at least about 0.5 weight-%sulfur, under hydrotreating conditions at about 2250 psig totalpressure, about 350 psig partial pressure of steam and about 700° F.,than said starting material; wherein a layer (a) of said impregnated,substantially spherical alumina-containing particles is placed assupport layer below at least one layer (b) of said hydrotreatingcatalyst particles; wherein said impregnated, substantially sphericalalumina-containing particles in said support layer are promoted with atleast one compound of at least one element selected from the groupconsisting of Y, La, Ce, Ti, Zr, Hf, Cr, Mo, W, Mn, Re, Ni, Co, Cu, Znand P, at a level of from about 0.1 to about 2.0 weight percent of saidat least one element; and wherein said hydrotreating catalyst particlescontain said at least one hydrogenation promoter at a level which iseffective for lowering the concentration of sulfur and metals present insaid hydrocarbon-containing feed stream under said hydrotreatingconditions.
 2. A process in accordance with claim 1, wherein saidcompounds of metals in said hydrocarbon-containing feed steam comprisecompounds of at least one metal selected from the group consisting ofnickel and vanadium.
 3. A process in accordance with claim 1, whereinsaid hydrocarbon-containing feed stream comprises about 3-500 ppmw Niand about 5-1000 ppmw V.
 4. A process in accordance with claim 1,wherein said hydrocarbon-containing feed comprises about 0.5-5.0weight-% sulfur.
 5. A process in accordance with claim 1, wherein saidhydrocarbon-containing feed stream contains from about 0.3 to about 20weight-% water.
 6. A process in accordance with claim 1, wherein saidhydrocarbon-containing feed stream contains from about 0.5 to about 10weight-% water.
 7. A process in accordance with claim 1, wherein saidstarting material used in step (A) has an initial average particlediameter in the range of from about 0.1 to about 1.0 inch, an initialsurface area in the range of from about 40 to about 600 m² /g, aninitial pore volume in the range of from about 0.2 to about 1.0 cc/g,and an initial normalized crush strength in the range of from about 100to about 400 lb. per inch diameter per particle.
 8. A process inaccordance with claim 7, wherein the initial content of Na in saidstarting material is less than about 1.0 weight-%, and said initialcontent of Al₂ O₃ is in the range of from about 90 to about 99 weight-%.9. A process in accordance with claim 1, wherein the concentration ofsaid at least one dissolved magnesium compound in the impregnatingsolution used in step (A) is in the range of from about 0.0001 to about2.0 mol/l, and the weight ratio of said starting material to saidimpregnating solution is in the range of from about 0.1:1 to about2.0:1.
 10. A process in accordance with claim 9, wherein said magnesiumcompound is magnesium nitrate and the concentration of dissolvedmagnesium nitrate in said impregnated solution is in the range of fromabout 0.01 to about 1.0 mol/l.
 11. A process in accordance with claim 1,wherein said heating in step (B) is carried out at a temperature in therange of from about 550° to about 800° C. for a period of time in therange of from about 10 minutes to about 20 hours.
 12. A process inaccordance with claim 1, wherein said substantially sphericalalumina-containing particles in layer (a) have a pore volume of poreshaving a diameter of about 40-200 Angstroms in the range of from 50% toabout 90% of the total pore volume, and a crush strength in the range offrom about 150 to about 350 lb. per inch diameter per particle.
 13. Aprocess in accordance with claim 1, wherein said impregnated,substantially spherical alumina-containing particles in layer (a) have asurface area in the range of from about 50 to about 300 m² /g and a porevolume in the range of from about 0.3 to about 0.8 cc/g, and containfrom about 0.06 to about 6.0 weight-% Mg.
 14. A process in accordancewith claim 1, wherein said at least one element is selected from thegroup consisting of Mo, Ni and Co.
 15. A process in accordance withclaim 1, wherein said refractory inorganic carrier comprises alumina,and said at least one hydrogenation promoter is selected from the groupconsisting of comppounds of Y, La, Ce, Ti, Zr, Cr, Mo, W, Mn, Re, Ni, Coand Cu.
 16. A process in accordance with claim 1, wherein saidhydrotreacting catalyst particles in layer (b) comprise alumina ascarrier material and at least one hydrogenation promoter selected fromthe group consisting of oxides and sulfides of Mo, oxides and sulfidesof Ni, oxides and sulfides of Co, and mixtures thereof, have a surfacearea in the range of from about 50 to about 500 m² /g, and have a porevolume in the range of from about 0.2 to about 2.0 cc/g.
 17. A processin accordance with claim 1, wherein another layer (a) of impregnated,substantially spherical alumina-containing particles is placed on top ofat least one layer (b) of hydrotreating catalyst particles.
 18. Aprocess in accordance with claim 1, wherein the weight ratio of eachlayer (a) of impregnated, substantially spherical alumina-containingparticles to each layer (b) of hydrotreating catalyst particles is inthe range of from about 1:100 to about 1:1.
 19. A process in accordancewith claim 1, whereinsaid hydrotreating conditions comprise a reactiontime in the range of from about 0.05 to about 10 hours, a reactiontemperature in the range of from about 250° to 550° C., a reactionpressure in the range of from about 0 to about 5,000 psig, and aquantity of added hydrogen gas in the range of from about 100 to about10,000 cubic feet of H₂ per barrel of hydrocarbon-containing feedstream.
 20. A process in accordance with claim 19, wherein saidhydrotreating conditions comprise a reaction time in the range of fromabout 0.4 to about 5 hours, a reaction temperature in the range of fromabout 300° to about 450° C., a reaction pressure in the range of fromabout 100 to about 2,500 psig, and a quantity of added hydrogen in therange of from about 1,000 to about 5,000 cubic feet of H₂ per barrel ofhydrocarbon-containing feed stream.
 21. A process in accordance withclaim 1, wherein said hydrocarbon-containing feed stream contains atleast one added thermally decomposable compound selected from the groupconsisting of compounds of metals belonging to Groups IIIB, IVB, VB,VIB, VIIB, VIII, IB and IIB of the Periodic Table.
 22. A process inaccordance with claim 21, wherein said at least one added thermallydecomposable compound is selected from the group consisting ofmolybdenum compounds, tungsten compounds, manganese compounds, chromiumcompounds, zirconium compounds and zinc compounds.
 23. A process inaccordance with claim 22, wherein said at least one thermallydecomposable compounds is at least one compound of molybdenum.
 24. Aprocess in accordance with claim 5, wherein said water is introduced assteam.
 25. A process in accordance with claim 1, wherein said feedstream has an API gravity, measured at 60° F., in the range of fromabout 5 to about
 30. 26. A process in accordance with claim 25, whereinsaid API gravity, is in the range of from about 8 to about
 25. 27. Aprocess in accordance with claim 1, wherein said at least one element ismolybdenum.
 28. A process in accordance with claim 27, whereinmolybdenum is present at a level of about 0.2 to about 1.0 weight-% Mo.29. A process in accordance with claim 1, wherein said temperature instep (B) is in the range of from about 550° to about 800° C.